so that when i export the file shows 2020-09-14T11:56:43 instead of 14-Sep-20 11:56:43 ?
That's because it's the raw data you're seeing. Domo will take that raw data and change how it's displayed in the cards itself. If you're wanting to export the raw data as a formatted string you'd need to create a beast mode to return the date formatted.
DATE_FORMAT(`Timestamp Column`, '%Y-%m-%d %H:%m:%S')